Intravesical real-time imaging and staging of bladder cancer: Use of optical coherence tomography.

592 | October-December 2008 | 3 in the laparoscopy group (P=0.02). However, Euro-QOL scores were comparable in the two groups at three and 12 months. The postoperative recovery was faster in the laparoscopy group as compared to the open group (41 vs. 62 days, P=0.04). The authors concluded that laparoscopic nephrectomy results in lesser postoperative pain, fewer late postoperative complications and faster return to normal activities than open nephrectomy.

3 in the laparoscopy group (P=0.02). However, Euro-QOL scores were comparable in the two groups at three and 12 months. The postoperative recovery was faster in the laparoscopy group as compared to the open group (41 vs. 62 days, P=0.04). The authors concluded that laparoscopic nephrectomy results in lesser postoperative pain, fewer late postoperative complications and faster return to normal activities than open nephrectomy.

COMMENTS
Laparoscopic nephrectomy has become a well-established option for localized renal tumors (T1-2N0M0) with a number of series reporting success equivalent to that of open surgery. Comparisons between laparoscopic and open radical nephrectomy have consistently shown advantages in favor of the laparoscopic approach with regard to all indices of peri-operative morbidity, including estimated blood loss (EBL), postoperative narcotic requirements, length of hospitalization and duration of convalescence. [1][2][3][4][5] However, most of the previously reported series were retrospective or non-randomized studies. This is the Þ rst prospective randomized trial comparing open and laparoscopic nephrectomy. The authors have also concluded in favor of laparoscopic nephrectomy regarding lesser postoperative pain, fewer late postopeartive complications and faster return to normal activities, as compared to open nephrectomy.
However, there are several limitations to the present study. The sample size in the two groups is too small to get statistically signiÞ cant results. The authors have included both benign and malignant renal disease for the nephrectomy. Complications associated with nephrectomy for renal malignancy may be different as compared to nephrectomy for benign renal disease. Parasitic vessels in renal tumors, with increased tumor size add to technical difÞ culty of laparoscopic nephrectomy, with increased risk of bleeding complications. The authors have not mentioned the reason of preferring transperitoneal approach to retroperitoneal approach, especially for benign renal disease and small localized renal tumors. The mean analgesic requirement in mg morphine equivalent (objective assessment of pain) of the two groups in the postoperative period should have been recorded along with visual analog scale (subjective assessment of pain), for better interpretation of postoperative pain in patients. Despite these shortcomings, the study conÞ rms previous Þ ndings in a more rigorous study design.

SUMMARY
In this retrospective study, the authors have assessed the application of optical coherence tomography (OCT) as an adjunct to conventional cystoscopy in the endoscopic evaluation of bladder tumors. From December 2005 to April 2007, 32 patients (25 men and seven women with median age of 59 years), majority of whom were known or newly diagnosed cases of bladder cancer, underwent OCT in addition to conventional rigid cystoscopy by a single surgeon. The US FDA-approved Niris Imaging System was used to acquire OCT images. The images of normal and suspicious areas were obtained prior to biopsy/resection using a flexible fiber optic probe inserted through the working channel of the rigid cystoscope. OCT images were obtained at representative portions of the lesion as well as at the junction of normal-appearing urothelium by placing the end-viewing optical probe perpendicular to the tissue and holding it in contact with the tissue for approximately 1.5 sec. The OCT image findings were interpreted intraoperatively at the time of the scan. Scan Þ ndings were later compared with the Þ nal pathologic diagnosis which was obtained by resecting the area of interest and submitting the tissue in formalin.
Images of a total of 38 suspicious areas were correlated with biopsy Þ ndings. Among 20 lesions staged as Ta on biopsy, OCT accurately identiÞ ed 18 whereas in two OCT overstaged the disease hence giving a sensitivity of 90% and speciÞ city of 89% for Ta lesions. OCT was able to demonstrate invasion in 11 out of 11 patients who had either lamina propria or muscle invasion. Among four lesions invading lamina propria on biopsy, OCT correctly diagnosed three whereas one was staged as T2 giving a sensitivity and speciÞ city of 75% and 97%, respectively. OCT accurately identiÞ ed muscle invasion in seven of seven biopsy-proven muscle-invasive tumors giving a sensitivity and speciÞ city of 100% and 90%, respectively. The negative predictive value of OCT for muscle invasion was 100%. In one patient Carcinoma in situ (CIS) on biopsy was correctly identiÞ ed by OCT, while it could be ruled out in another by OCT. OCT was able to differentiate malignant from benign lesions with a positive predictive value of 89% and negative predictive value of 100%.
Based on the above Þ ndings, the authors concluded that OCT is a rapid, real-time, high-resolution, easy-to-use tool that can help differentiate Ta and T1 tumors and identify muscle-invasive bladder tumors.

COMMENTS
Conventionally, white light cystoscopy in combination with transurethral resection is used for assessing depth of tumor penetration. [1] Unfortunately, the frequency of tumor understaging is relatively high. In one study, 40% of patients with non-muscle-invasive clinical stage had muscleinvasive disease as conÞ rmed by the Þ nal pathological report obtained after radical cystectomy. [2] Other imaging modalities including computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound have limited ability in resolving the microstructural detail required to assess subtle changes in the bladder wall.
OCT, a technology already in use in the diagnosis of ophthalmological diseases, has been investigated as a tool for staging bladder cancer in this study. It is analogous to ultrasound B mode imaging except that it uses near infrared light as opposed to sound waves. [3] With a resolution of 10 to 20 μm, it is akin to using an optical microscope and micro-architectural features of the bladder wall can be seen. [4] The images obtained are cross-sectional and in real-time. As the depth of penetration is only 1 to 2 mm, though it is able to distinguish structural changes in the bladder wall involving the mucosa, lamina propria, and superÞ cial muscularis properly, information on invasion of deeper layers and extravesical spread is not available. [5] In the OCT image, the mucosa generally appears as a dark, thin, clearly deÞ ned layer. The lamina propria gives a bright, distinct signal, whereas muscularis shows a darker, spindled appearance. [1] Key beneÞ ts of OCT are live sub-surface images at nearmicroscopic resolution, without the hazard of ionizing radiation and without the need for any preparation of the sample.
In the future OCT may Þ nd an application in the early diagnosis and screening of mucosal malignancies. It may also have a potential role in conÞ rming completeness of resection after transurethral resection of bladder tumour (TURBT) once images obtained from tissues affected by heat are standardized.